A new report from the Opera ad network shows that it’s more profitable for content providers to advertise on iOS than on Android.

Opera, which also distributes web and mobile browser software, released the report on July 19. It cites metrics from its own network including eCPM, the revenue a publisher earns per thousand ad impressions. While Android ads earned an average of $2.10 per thousand in the US in the second quarter of 2012, iOS ads earned $2.49 per thousand.

The “State of Mobile Advertising” report showed iOS and Android leading other mobile operating systems by a large margin.

When separated out, the iPad, running Apple’s iOS, showed an even higher eCPM of $3.96. The iPhone by itself took in $2.85 per thousand ad impressions. The iPod Touch, the only other device running iOS, was not shown in the executive summary of the report. The authors of the report hypothesize that the iPad’s large screen helped drive its eCPM up.

“We also see the importance of device market share in encouraging advertisers to target particular devices,” the report said. “Windows phones have most if not all of the advanced features of Android and iPhones, but low levels of user adoption stifle its performance.”

eCPM in the United States averages out to $1.98, compared with $1.90 for the world as a whole. 73 percent of all ad requests come from the US and Canada, with another 13 percent from five European Union countries (United Kingdom, Italy, Spain, Germany, and France). Excluding North America and Europe, the average eCPM is $1.57. Asia Pacific made up another 10 percent of ad requests.